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Background: The effect of malaria infection on the immunogenicity of the recombinant vesicular stomatitis virus-Zaire Ebola virus envelope glycoprotein (GP) vaccine (rVSVΔG-ZEBOV-GP) (ERVEBO) is unknown.Methods: The Sierra Leone Trial to Introduce a Vaccine Against Ebola (STRIVE) vaccinated 7998 asymptomatic adults with rVSVΔG-ZEBOV-GP during the 2014-2016 Ebola epidemic. In STRIVE's immunogenicity substudy, participants provided blood samples at baseline and at 1, 6, and 9-12 months. Anti-GP binding and neutralizing antibodies were measured using validated assays. Baseline samples were tested for malaria parasites by polymerase chain reaction.Results: Overall, 506 participants enrolled in the immunogenicity substudy and had ≥1 postvaccination antibody titer. Of 499 participants with a result, baseline malaria parasitemia was detected in 73 (14.6%). All GP enzyme-linked immunosorbent assay (ELISA) and plaque reduction neutralization test (PRNT) geometric mean titers (GMTs) at 1, 6, and 9-12 months were above baseline, and 94.1% of participants showed seroresponse by GP-ELISA (≥2-fold rise and ≥200 ELISA units/mL), while 81.5% showed seroresponse by PRNT (≥4-fold rise) at ≥1 postvaccination assessment. In participants with baseline malaria parasitemia, the PRNT seroresponse proportion was lower, while PRNT GMTs and GP-ELISA seroresponse and GMTs showed a trend toward lower responses at 6 and 9-12 months.Conclusion: Asymptomatic adults with or without malaria parasitemia had robust immune responses to rVSVΔG-ZEBOV-GP, persisting for 9-12 months. Responses in those with malaria parasitemia were somewhat lower. [ABSTRACT FROM AUTHOR]

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]

The Sierra Leone Trial to Introduce a Vaccine against Ebola (STRIVE), a phase 2/3 trial of investigational rVSV∆G-ZEBOV-GP vaccine, was conducted during an unprecedented Ebola epidemic. More than 8600 eligible healthcare and frontline response workers were individually randomized to immediate (within 7 days) or deferred (within 18-24 weeks) vaccination and followed for 6 months after vaccination for serious adverse events and Ebola virus infection. Key challenges included limited infrastructure to support trial activities, unreliable electricity, and staff with limited clinical trial experience. Study staff made substantial infrastructure investments, including renovation of enrollment sites, laboratories, and government cold chain facilities, and imported equipment to store and transport vaccine at ≤-60oC. STRIVE built capacity by providing didactic and practical research training to >350 staff, which was reinforced with daily review and feedback meetings. The operational challenges of safety follow-up were addressed by issuing mobile telephones to participants, making home visits, and establishing a nurse triage hotline. Before the Ebola outbreak, Sierra Leone had limited infrastructure and staff to conduct clinical trials. Without interfering with the outbreak response, STRIVE responded to an urgent need and helped build this capacity.Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220]. [ABSTRACT FROM AUTHOR]